Instrument case lock



July 15,1941. N J, SMITH 2,249,438

INSTRUMENT CASE LOCK Filed March 21, '1939 l IIVI') M V////////.

Witness mentor Patented July 15, 1941 INSTRUMENT CASE LOCK Norman J. Smith, Medfield, Mass., assignor to Crosby Steam Gage & Valve Company, Boston, Mass, a corporation of Massachusetts Application March 21, 1939, Serial No. 263,226

1 Claim.

The present invention relates to a simple and adequate locking means for the swinging front of instrument cases, such as recorders, gauges, and the like.

The purpose of the invention is to provide an easily operated and adequate lock which holds the front of the case securely and cannot be readily tampered with by unauthorized persons.

With this and other objects in view, various features of the invention consist in certain novel features of construction, combinations and arrangements of parts hereinafter described and claimed, the advantages of which will be obvious to those skilled in the art from the following description.

In the accompanying drawing illustrating the preferred form of the invention Figs. 1 and 2 represent front and side elevations, respectively, of a chart recorder having the new form of locking device; Fig. 3 is a detail illustrating in full lines the cam lock for the swinging door in locked position; Fig. 3 is a detail illustrating the cam lock in open or receiving position; Fig. 4 is a detail illustrating a section of the device for holding the lock in closed position; Fig. 4 is a section of the device with the door in open position and Fig. 5 is a view similar to Fig. 4, illustrating the details of the locking stud and the application of a suitable instrumentality for operating.

As indicated clearly enough in Figs. 1 and 2, the device is applied to a chart recorder of circular conformation having a housing portion l0, and a front door l2 hinged at M, provided with a transparent glass [6 and locked opposite the hinge through the improved locking device indicated generally in Fig. 3. The instrument is provided in the usual manner with the indicating chart l8 of appropriate form, with a recording pen 2!). r

As will be evident from the drawing, the door is secured or latched in closed position by a latch device comprising an operating handle or bar 22 mounted upon a shaft 24 exteriorly of the case, as shown in Figs. 1 and 2. The latching device per se is supported upon the shaft at the inner side of the case and comprises essentially a latch member 26, having a camming slot 28 designed to receive and to engage with a latch pin 30 mounted upon the inside of the housing 10. When the instrument is in an installed vertical position, the latch member 26 due to its unbalanced condition, normally seeks the position shown in dot-and-dash lines. in Fig. 3, with e op face 32 resting against the inner rim.

of the door as indicated in Fig. 3. In this position the mouth of the camming slot is normally aligned with the latch pin or stud 30 as the door is swung into closed position. Thereafter turning the handle 22 revolves the latch member 26 from the position shown in dotted lines to the position shown in full lines in Fig. 3. This brings the latch pin into the'relative position in the camming slot as indicated therein. In the closed or latched position, as shown in full lines in Fig. 3, the latch pin rests at the lower end of the slot which is substantially developed upon the arc of revolution of the latch member, as will be evident from an inspection of the drawing. The latch member may be locked in this position, if deemed desirable, by a locking wedge 40 which, as shown particularly in Figs- 3 to 5, is mounted on the inner end of a stud 42 engaged by a fiat spring 44 to hold it in any position to which it is turned. This locking wedge when turned to the position shown in full lines in Fig. 3, retains the latch in closed position and prevents any opening of the door without first releasing the lock. As indicated more particularly in Fig. 5, the locking stud 42 is seated in a sleeve 45 terminating flush with the front of the instrument, as shown in Fig. 1. The outer or engaging end of the locking stud is squared at 46 and is surrounded by an opening of appropriate shape formed in the sleeve, so that the stud may be engaged and turned by an operating instrumentality suitably shaped but by no other, such an instrument being indicated in section at 48 in Fig. 5. Obviously, when so locked the latch can only be disengaged by first turning the lock to inoperative position, after which the latch may be disengaged manually without the aid of an instrumientality.

Having thus described the invention, I claim:

A look for an instrument case having a stationary housing portion and a swinging front portion, a latch member pivotally mounted on the front portion and having an open-ended camming slot, a stationary latchp-in positioned at the inside of the housing portion adjacent the rim, the latch member in the vertical position of the instrument normally seeking a position by gravity in which the open mouth of the camming slot is aligned with the latch pin upon closure of the front portion, a handle mounted exteriorly of the front and connected with the latch member, the handle serving to rotate the latch member after closure of the front portion and entrance of the latch pin into the camming slot, the turning movement of the latch memher drawing the front portion into secure relation through the action of the camming slot in drawing the latch pin toward the pivot of the latch member, a locking wedge movable in a plane angularly disposed to the plane of movement of the latch member and engaging behind the latter when in closed position to prevent movement therefrom, and an operating stud for the locking Wedge extending flush with the exterior of the case and designed to be engaged by an operating instrumentality of predeter- 5 mined shape.

NORMAN J. SMITH. 

